Planophile (/ˈplenoʊfaɪ̯l/).
From Proto-Indo-European *pleh₂-no-s (“
flattened”) and the
ancient greek word phílos (love).
A planophile is someone who has an
obsession with the word "flat" and things being flat.
They commonly incorrectly conflate it with the word "level".
A flat earther is a good example of a planophile.